Switch-board and central-office apparatus



(No Model.)

T. B. DOOLITTLE.

SWITGH BOARD ANDUENTRAL OFFICE APPARATUS. No.339,626. Patented Apr. 13, 1886.

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THOMAS B. DOOLITTLE, OF BRIDGEPORT, CONNECTICUT.

SWITCH-BOARD AND CENTRAL-OFFICE APPARATUS.

EPECIPICATION forming part Of Letters Patent NO. 339,625, dated April 13, 1886.

Application filed November 28, 1885. Serial No. 184,140. (No model.)

To all whom it may concern;

Beit known that I, THOMAS E. DOOLITTLE, residing at Bridgeport, in the county of Fairfield and State of Connecticut, have invented certain Improvements in Switch-Boards and Central-Office Apparatus, of which the following is a specification.

This invention relates to switch-boards and connecting devices for telephonic intercommunication systems.

In a separate case filed on the same day with the present one I have shown, described, and claimed a complete system of intercommunication in which a number of central telephonestations each having converging telephonelines are united by long extramural or trunk lines, so that substations connected with either central station may communicate with those belonging to other central stations.

I have in the said separate specification described the general characteristics of the switch-boards at the several central stations. at the principal or terminal stations of a series of trunk lines I provide, in addition to the regular or operating switch-board, at which the trunk lines may be connected with any of the local convergent lines, a testing or termiuni-changing switch-board, to which all entering lines are first connected, and from whence they may at the will of the circuit-manager be directed to the anuunciators and connecting springjacks on the operating-board. The lines each terminate in flexible conductingcords and connecting-plugs, which may be inserted inmetallic sockets, these sockets each connecting either by loop or singie lines with an annunoiator and spring-jack upon the operating switchboard, which is in turn furnished with plugs and cords arranged in pairs for the purpose of uniting any two lines, this being accomplished by inserting the two plugs of any pair of connectorsin the respective springjacks of the lines to be connected. The necessary devices for sending call-signals and supervising conversations are by suitable switches or circuitchangers adapted to be temporariiy included in any of the pairs of cords, and, if desired, in a manner well understood by those skilled in the art, the electro-magnet of an annnnciator may be included in the circuit of each pair to be operated, in order to announce that disconnection is desired. The switch-boards adopted at intermediate central stations are not in the said contemporary case described in detail, but are generally stated to be of a compound order combining themselves measurably, the functions of both testing and operating switch-boards at the principal central stations-that is, the entering lines from every point of the compass, each terminate at the switchboard (where they are readily interchangeable) in a separate and. independent conducting cord and plug, while separate pairs of conducting cords and plugs are provided for the interconnections of any two of such lines with one another or with convergent lines.

The present invention embodies the details of the combinations by which these instru mentalities are condensed in a single switchboard.

The object aimed at is to provide more efficient devices for the speedy interchange of lines at an intermediate central station. Assuming that such an intermediate station lies in the route between New York and Boston, and that between those points (each of which is provided with both testing and operating switch-boards) four metallic or double-wire circuits extend. Let it, moreover, be as sumed that between the said intermediate station and one of the terminal stations are one or more local single-wire lines. At the two terminal stations are circuit-managers or skilled operatives who connect and crossccnmeet the several lines as disabilities or circuit faults may render requisite or admissible. At the intermediate stations, however, it frequently occurs that operators or agents of very ordinary acquirements are stationed. These persons are required, at the order of the circuit-managers at the terminal stations, from time to time to make certain similar changes, and it is therefore necessary to provide at such pointsdevices of such simple character as to be readily comprehended, and such as are specially easy and facile of manipulation.

One of the lines of a double-wire circuit may,for examplabe out of order between one 100 of the terminal stations and the first intermediate station, and it becomes necessary, to prevent a stoppage of the business, to throw the disabled portion out of circuit altogether and to substitute a perfect wire in the main line between the two said stations. One of the local lines may be temporarily used for this purpose, and the circuit manager at the principal station will first make the change himself and then give the order to the operator at the intermediate station. The lines are in practice all designated wit-h a special number, and are so marked; and it is for the dispatch of business desirable that an order couchedin some concise terms-such as disconnect No. 1 east and connect-No. 9 east in its placeshall be at once understood and instantly complied with.

In accordance with the above this invention consists in embodying in a single elec tric switch-board connecting cords and plugs placed at one side of the switch-board, each representing a single-line terminal, annunciators and connecting devices each provided with one or more sockets for the reception of the said line-terminal plugs, and a series of pairs of conducting-cords and plug-connectors arranged upon the other side of the switchboard and adapted to be used for connecting any two lines together for connection.

In the drawings which are filed herewith, and which form aportion of this specification, Figurel is a vertical cross-section of a switchboard embodying my invention. Fig. 2shows a portion of a front view of the said switchboard with the paired connecting-cords. Fig. 3 is a drawing of a rear view of a similar switchboard, showing the line terminal cordconductors, together with the plugs and the plug-sockets constituting the annunciator and spring-jack terminals; and Fig. 4 is a diagram showing the connections of a line-terminal cord, annunciator, spring-jack, and connecting-cord.

In the drawings, A is the table, and B the vertical portion of a switchboard supported upon suitable standards, M. The table or horizontal front board is continued to the rear of the vertical portion by a shelf, 0, which is perforated with holes for theline-terminal cords to pass. A series of terminal plugs, 1', rest by the" may be screw-threaded, as in the plugs 13" and i. A series of shelves, a, are fixed across the upper or vertical part, B, of the switchboard, and support each a number of combined annunciators and spring-jacks, b, each of which steers is provided with plug-sockets s s, for the insertion of theplug ends If the tapered plug ends are employed, the holes are merely tapered inwardly and the plugs i are inserted and given a half-turn to tighten them; but if the plugs are screw-threaded, as in i and t, the sockets are correspondingly threaded with a female screw, and the plugs can then be screwed therein.

Those annunciators which are intended for metallic circuits have both of their circuit terminals attached to the above described sockets s and s, and in Fig. 3 the two lower and the upper rows are so represented, while the second row from the top is assigned to grounded circuits, and is shown as having but the lower socket, s, the uppersocket being replaced by a binding-screw, r, all of the said binding-screws being united by wire and also connected with the ground-wire j. The drops or shutters c of the annunciators are at the front of the board. Two of theincoming lines, 3 and at, are shown as being connected with one of the annunciator-s by their plugs, which are inserted in the two sockets thereof, the weights to of the attached cords being thus pulled up, as shown. Line 12, by means of its terminal cord and plug i, is in the same way connected with the grounded annunciator on the third upward shelf.

The first case represents the two wires of a metallic circuit, and the second the singleline of a grounded circuit. All of the working lines in like manner are united with some one annunciator, but may with the utmost facility be changed to any other annunciator; or either wire of a metallic circuit it is obvious can readily be withdrawn from any socket and any other given line represented by the proper cord and plug substituted therefor.

The two loops of a metallic circuit, running, for example, east and west, may normally be connected with two separate annunciatorsthat is to say, the two wires, Nos. 1 and 2 east, may be connected with one annunciator, and the two wires Nos. 1 and 2 of the western loop may by means of two separate plugs and cords be connected with another annunciator.

WVhen it is desired to connect any two lines or two sections of athrough-line together, excluding the annunciator at the way or intermediate office or station altogether, the sockets h,which are arranged on the rear edge of the shelves c, are used. These are connected together in pairs by permanent connections, and the plugs of the wiresto be connected are inserted in the two sockets of a pair, thus giving direct communication without any intermediate electro-magnet-s; or if the four ends of a metallic circuit are to be so united, these being represented by four adjacent plugs and cords, four sockets will ofcourse be required, h, h", h and h. The two plugs forming the terminals of the two wires from one direction may be inserted into the first and third or first and fourth sockets, and the two plugs forming the terminals of the two wires from the other direction are then placed in the two remaining sockets.

In Fig. 2 a portion of the front of the switchboard is shown, I) representing the combined annunciator and spring-jack, and c the shutter or drop thereof. The cordszand c at the front of the board are used exclusively to connect any two of the lines together for com mu nication. They are oftwo classes-i 6., double conductor for the interconnection of metallic circuits, and single conductor for the interconnection of single-wire lines. The former class is represented by the letter 5, and the con ducting-cords are terminated by the double conductorplugs e, the cords extending through holes in the table A, as already explained in connection with the rear shelf, 0. The other class is represented by z, and each cord ends in a solid plug connector, g. All are connected in pairs, and a pair of single conductor-cords is rcqui red to connect two single lines together, which is accomplished by inserting one of the plugs ginto the spring-jack t of one of the lines to be connected and the other plug 9 into the springjack f of the other line. The metallic circuits are united in the same way.

It is not thought necessary to show or describe the various calling and supervising devices in this specification, since they form no part of my present invent-ion.

The spring-jacks and annunciators I employ are preferably combined in one organization, as described in a separate application filed of even date herewith.

[n Fig. 4c the relative functions of the two series of conductingcords areindicated. The letters of reference represent the same parts as in the other figures. The line represented by the cord 3/ is connected by the plug y with i the sockets of the annunciator. This connects bywiredwith onesidc ofthespring-jack,which normally rests in the case of a metallic circuit jack in contact with a portion of the metallic frame. The frame is united by wire 7 with one wire of the annunciator-magnet 12, while the other wire of the said magnet is united by wire 8 with the remaining terminal socket s. The plug 9' of the other mainline cord 1/ is inserted in this socket, thus completing the circuit.

One of the connectingcords at the front of the board is shown with its plug 6 inserted in the springjack u, the other plug of the same pair being at rest on the table A.

1. The combination, in a switch-boaithoi' a series of flexible conductors and plug-connectors therefor, constituting line-terminals, with a second series of flexible conductingcords, provided also with plugs arranged in pairs, the two cords of each pair forming a continuous conductor or pair of conductors, and adapted thereby to act as a connectinglink bet-ween any two circuits, substantially as and for the purposes specified.

2. The combination, in an electric switchboard, of line-terminals comprising flexible conductors and plug-connectors, plugsockets constituting the terminals of annunciators and adapted to receive the line-terminal plugs, whereby the said aminnciators are connected in the line-circuits, springjacks, one for each annunciator, included in the circuit of the said annunciator between any two of the said sockets, and a series of pairs of connecting cords and plugs, each pair constituting a continuous conductor with a plug at each end thereof, which plugs are adapted for insertion in the spring-jacks of any two lines, substantially as described.

3. The combination, in an electric switchboard of short station-loops, each including an annunciator and a springjack, and terminating in two plug-sockets, one for each end of the said loop, of plug-connectors at the end of flexible cords, each plug constituting the terminal of a line-wire and adapted for insertion in one of the said sockets, and a series of sockets, h, united in pairs, also adapted to receive the said plugs, whereby the several lineterminals may be readily connected with any annunciatorloop, with any other line through the said loop, or with any other line direct, snbstantiall y as specified.

4. In an electric switch-board, a series of plugs and flexible cords, each forming the terminal of a separate line-wire, a series of pairs of plug-sockets therefor, each pair constituting the terminals of an annunciator, and a separate series of single-plug sockets constituting one terminal of an annunciator, the other terminal of which is attached toagroundconnection, whereby the said line-terminals may be united in pairs to form a metallic circuit through any of the first series of annunciators, or connected to ground through any annunciator, as herein described. f

5. An electric switch-board comprising annunciators and spring-jacks, the said annullciators being furnished with terminal sockets at the rear side of the switchboard, the spring-jack orifice opening upon the front side of the same, a series of plug-connectors and flexible conductors, each forming a separate line-wire terminal located at the rear of said switch-board and adapted to unite any of the said line-terminals to any of the said ann'unciators by means of the terminal sockets thereof, and a series of paired plug-connectors and flexible conductors located at the w front of said switch-board, the said plug-connectors being adapted to be inserted in the springjack orifices to connect any two of the lines together, substantially as hereinbefore described.

6. An electric switch-board having on each i side thereof a separate series of flexible cords i and connecting-plugs arranged as described, i the plugs and flexible conductors at the rear,

each constituting asingle-line terminal, and In testimony whereof I have signed my those at the front side being arranged in pairs name to this specification, in the presence of for the interconnection of any two circuits, two subscribing witnesses, this 23d day of together with annunciators and springacks November, 1885. 5 mounted on the said board and having coinnion terminal sockets,which sockets are adapt- THOMAS B. DOOLITTLE. ed to receive any of the line-terminal plugs, the spring-jacks being in like manner adapted Witnesses: to receive the connecting-plugs, substantially GEO. H. E. TROUVELOT, IO as hereinbefore specified, and for the purposes i GEO. \VILLIS PIERCE.

set forth. 

